RING finger, H2 subclass, found in Arabidopsis thaliana RING-type E3 ubiquitin transferase BIG BROTHER (BB) and similar proteins
BB (also known as protein ENHANCER OF DA1-1 or EOD1) is an E3 ubiquitin-protein ligase that limits organ size, and possibly seed size, in a dose-dependent manner. It negatively regulates the duration of cell proliferation in leaves and petals independently of the major phytohormones (e.g. auxin, cytokinin, gibberellin, brassinosteroids, ethylene, abscisic acid, jasmonic acid), probably by targeting growth stimulators for degradation. It limits the proliferation of root meristematic cells. BB polyubiquitinates DA1. It is involved in the promotion of leaf senescence, in addition to its function in restricting plant growth. BB-related is an E3 ubiquitin-ligase probably involved in organ size regulation. Members of this subfamily contain a C3H2C3-type RING-H2 finger.
Comment:C3H2C3-type RING-H2 finger consensus motif: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-H-X2-C-X(4-48)-C-X2-C, where X is any amino acid and the number of X residues varies in different fingers
Comment:A RING finger typically binds two zinc atoms, with its Cys and/or His side chains in a unique "cross-brace" arrangement.
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